Interspinous process fusion device and method of use

ABSTRACT

The present invention discloses an interspinous process fusion device, a method of fabricating the interspinous process fusion device, and a surgical method for maintaining a space between two spinous processes in a spine of a patient using the fusion device. The interspinous process fusion device including a distal tip member, a middle plate, a proximal plate, an elongate member, and a plurality of movable wings. The elongate member having a first end, a second end, and a longitudinal axis extending between the first and second end. The distal tip member is connected to the first end of the elongate member, the proximal plate is connected to the second end of the elongate member, and the middle plate and plurality of wings are positioned intermediate the distal tip member and the proximal plate along the longitudinal axis to form the interspinous process fusion device assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 15/211,600, filed Jul. 15, 2016, which is acontinuation application of U.S. patent application Ser. No. 14/349,118,filed Apr. 2, 2014 (U.S. Pat. No. 9,393,053), which is a national stagefiling under section 371 of International Application No.PCT/US2012/058478 filed on Oct. 2, 2012, and published in English onApr. 11, 2013 as WO 2013/052496 A2 and claims priority benefit under 35U.S.C. § 119(e) of U.S. Provisional Patent Application No. 61/542,512filed Oct. 3, 2011, which are each incorporated herein by reference intheir entireties.

TECHNICAL FIELD

The present invention relates generally to general surgery, orthopaedicand neurosurgical implants used for insertion within a space betweenhard tissue structures, and more specifically, but not exclusively,concerns devices implanted between interspinous processes to maintain orreestablish proper spacing within the spine.

BACKGROUND OF THE INVENTION

Fusion of the lumbar and thoracic spine currently involves eitherfixation posteriorly using pedicle screws or anteriorly using plates orrods applied directly to the vertebral bodies. Often these require majoropen exposures and extensive dissections of soft tissues. Recently,instrumentation and implants have been developed which enable bothfusion and fixation to be performed through minimally invasivetechniques, however, fixation with pedicle screws or anterior plateswhen performed with minimally invasive (MIS) techniques requiressignificant technical skill. Surgical errors and/or procedures performedwith less than advanced surgical technique often results in patientmorbidity.

Interspinous process fusion techniques have also been developed.However, these surgical techniques also require moderate to significantsoft tissue dissection and there are not true corresponding MISinterspinous process implants.

SUMMARY OF THE INVENTION

Advancement of the state of interspinous process implants and therelated MIS surgical technique are believed desirable. The disclosedembodiment is designed to enable interspinous process fixation using MIStechniques. In doing so, it will eliminate the technical difficultiesinherent to MIS instrumentation with pedicle screws, as well as the softtissue dissection experienced with ALIF or open interspinous processfixation.

The present invention provides in one aspect, an interspinous processfusion device that has a distal tip, a middle plate, a proximal plate,an elongate member having a first end and a second end and alongitudinal axis that extends between the first end and the second end,and a plurality of movable wings. The distal tip member is connected tothe first end of the elongate member and the proximal plate is connectedto the second end of the elongate member with the middle plate andplurality of wings being positioned intermediate the distal tip memberand the proximal plate along the longitudinal axis.

The present invention provides in another aspect a method of fabricatingan interspinous process fusion device, the method may include the stepsof obtaining an elongate member having a first end and a second end. Themethod may also have the step of obtaining a distal tip member, a middleplate, a proximal plate, a first pair of wings, and a second pair ofwings. A further step may be connecting the proximal plate to the secondend. An additional step may also be inserting two actuation screwsthrough corresponding openings in each of the first pair of wings, thetwo actuation screws being detachably connected to the proximal plate.The method may also include the steps of inserting the elongate memberand the two actuation screws through a plurality of openings in themiddle plate to position the middle plate adjacent to the first pair ofwings and inserting the two actuation screws through correspondingopenings in each of the second pair of wings. The method may furtherinclude the step of connecting the distal tip member to the first end ofthe elongate member to form the fusion device

The present invention provides in another aspect, a surgical method formaintaining a space between two interspinous processes, the method mayinclude the step of obtaining a medical device that has a distal tipmember, a middle plate, a proximal plate, an elongate member having afirst end and a second end and a longitudinal axis extending between thefirst end and the second end, and a plurality of movable wings. Themethod may also include the step of inserting the medical devicethorough an opening in the skin of the patient. A further step of themethod may be positioning the medical device between a top spinousprocess and a bottom spinous process. The method may also include thestep of moving the plurality of wings to pressingly engage the topspinous process and the bottom spinous process to maintain the spacebetween the top and bottom spinous processes.

Further, additional features and advantages are realized through thetechniques of the present invention. Other embodiments and aspects ofthe invention are described in detail herein and are considered a partof the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a posterior, distal perspective view of one embodiment of aninterspinous process fusion device, in accordance with an aspect of thepresent invention;

FIG. 2 is a posterior, lateral perspective view of the interspinousprocess fusion device of FIG. 1, in accordance with an aspect of thepresent invention;

FIG. 3 is an exploded view of the interspinous process fusion device ofFIG. 1, in accordance with an aspect of the present invention;

FIG. 4 is a lateral view of the interspinous process fusion device ofFIG. 1 showing the wings angled at 210 degrees as determined from afully retracted position, in accordance with an aspect of the presentinvention;

FIG. 5 is a lateral view of the interspinous process fusion device ofFIG. 1 showing the wings angled at 150 degrees as determined from afully retracted position, in accordance with an aspect of the presentinvention;

FIG. 6 is a posterior, lateral perspective view of the interspinousprocess fusion device of FIG. 1 showing the locking insert and centerbolt prior to insertion into the device assembly, in accordance with anaspect of the present invention;

FIG. 7 is a posterior, lateral perspective view of the interspinousprocess fusion device of FIG. 1 showing the device in a collapsedposition prior to insertion between two spinous processes, in accordancewith an aspect of the present invention;

FIG. 8 is a medial view of the inner aspect of the distal tip of theinterspinous process fusion device of FIG. 1, in accordance with anaspect of the present invention;

FIG. 9 is a medial view of the distal tip showing the coupled inferiorand superior actuation screws and the locking insert with central boltinserted, in accordance with an aspect of the present invention;

FIG. 10 is a posterior view of the interspinous process fusion device ofFIG. 1, following implantation between two spinous processes, inaccordance with an aspect of the present invention;

FIG. 11 is a lateral or side view of the interspinous process fusiondevice of FIG. 1, following implantation between two spinous processes,in accordance with an aspect of the present invention;

FIG. 12 is a side view of a cutting tool to open the space for theexpansion of the wings, in accordance with an aspect of the presentinvention;

FIG. 13 is a front view of the cutting tool of FIG. 12, in accordancewith an aspect of the present invention; and

FIG. 14 is top and side views of a set of dilators, in accordance withan aspect of the present invention.

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

Generally stated, disclosed herein is an interspinous process fusiondevice that typically includes a distal tip, a middle plate, a proximalplate, four fins or wings and three securement screws. As used herein,the terms “interspinous process fusion device”, “device”, “fusiondevice”, “implant” and “fusion implant” may be used interchangeable asthey essentially describe the same type of device. Further, a method ofassembling the device is discussed. Finally, also described herein is asurgical method for using the interspinous process fusion device tomaintain a space between two vertebral bodies within a patient sufferingfrom a diseased or damaged spinal column.

In this detailed description and the following claims, the wordsproximal, distal, anterior, posterior, medial, lateral, superior andinferior are defined by their standard usage for indicating a particularpart of a bone or implant according to the relative disposition of thenatural bone or directional terms of reference. For example, “proximal”means the portion of an implant nearest the torso, while “distal”indicates the portion of the implant farthest from the torso. As fordirectional terms, “anterior” is a direction towards the front side ofthe body, “posterior” means a direction towards the back side of thebody, “medial” means towards the midline of the body, “lateral” is adirection towards the sides or away from the midline of the body,“superior” means a direction above and “inferior” means a directionbelow another object or structure. In addition, for the purposes of thisdisclosure when referencing the device, the term “proximal” will meanthe portion of the device closest or nearest the insertion instrument.The term “distal” shall mean the portion of the device farthest awayfrom the insertion instrument.

Referring now to FIG. 1, an example of the interspinous process fusiondevice 100 is shown. The device 100 as seen in FIGS. 1, 2 and 3 has agenerally cylindrical geometry with a substantially straight externalprofile and bulbous or bullet shaped end to facilitate insertion betweentwo spinous processes. The implant 100 may likely include a distal tipmember 110, a middle plate 120, a plurality of fins or wings 130 and aproximal plate 140.

As seen in FIG. 2, for example purposes the device 100 includes inaddition to the above noted elements, a locking insert 150, an innerlocking screw or central bolt 170 and superior and inferior actuationscrews 160. FIGS. 1 and 2 also show a means for fixation 180 disposed onthe inner surface of wings 130. The means of fixation 180 may includebut not be limited to spikes, pins, teeth and aroughed/textured/irregular/grid surface. The means for fixation 180facilitates the capture and securement of the spinous processes betweenthe wings when they are expanded.

As depicted in the exploded view of FIG. 3, the device 100 includesdistal tip member 110, a middle plate 120, a plurality of fins or wings130 and a proximal plate 140 with a locking insert 150, an inner lockingscrew 170 and superior and inferior actuation screws 160. Briefly, thedistal tip member 110 includes a generally bullet or convex shaped endwith a planar surface at the opposite end of the member. The convex endis shaped to facilitate insertion into the body during the operativeprocedure as well as between the two adjacent spinous processes. Theplanar end is configured to facilitate the actuation of the two adjacentwings 130 when the device 100 is assembled. As seen in FIG. 8, theplanar end may include, for example purposes, two outer holes 210 intowhich the superior and inferior actuation screws may be threaded toactuate and secure the positioning of the wings. The central hole 220 issized to receive the inner locking screw following assembly of thedevice 100. The central depression 230 is configured to receive thelocking insert after the locking insert has been positioned through thecentral aspect of the assembled device 100.

FIG. 9 shows a perspective view of the device 100 with the wings 130,the middle plate 120 and the proximal plate 140 removed. The superiorand inferior actuation screws 160 are seen inserted into thecorresponding securement holes 210 disposed in the inner planar surfaceof the distal tip member 110. Additionally, the locking insert 150 isshown positioned within the central depression 230 with the innerlocking screw 170 threaded through the locking insert 150 and into thecentral hole 220 (not shown).

As seen in FIG. 3, the middle plate 120 may have two planar ends tofacilitate the assembly of the device 100. The two ends will articulatewith two pairs of wings when the device 100 is constructed. The outershape of the middle plate 120 is oval or oblong to accommodate insertionbetween the two spinous processes, although other geometric shapes mayalso be used depending upon the clinical situation. The thickness of themiddle plate 120 may vary depending upon the clinical situation andpatient size. For example purposes, the middle plate thickness may rangebetween 3-25 mm, with a preferred range of 3-15 mm. Superior andinferior screw holes extend through the entire thickness of the plate toaccommodate the passage of the corresponding actuation screws 160. Thereis a centralized opening that is sized to permit the insertion of thelocking insert 150 that then transacts the thickness of the middle plate120 and extends into the proximately positioned distal tip member 110for securement.

It should be understood that device 100 may include more than oneintermediate spacer plates as shown. Although the device 100 isdescribed as having a single middle plate 120, a plurality of suchplates 120 may be used in the device construct depending upon apresented clinical situation.

Also shown in FIG. 3 is the proximal plate 140. The proximal plate 140may be similarly constructed to the middle plate 120 in that it may havetwo planar ends to facilitate the assembly of the device 100. The innerend surface of the proximal plate 140 may articulate with one pair ofwings when the device 100 is constructed. The outer end comprises theend aspect of the device 100. The outer shape of the proximal plate 140is oval or oblong to accommodate placement between the two spinousprocesses, although other shapes may also be used depending upon thepatient's anatomy. The thickness of the proximal plate 140 may varydepending upon the clinical situation and patient size. For examplepurposes, the proximal plate may have a thickness ranging from 2-25 mm,with a preferred thickness range of 2-10 mm. Superior and inferior screwholes extend through the entire thickness of the plate to accommodatethe passage of the corresponding actuation screws 160. These holes alsomay include a counter bore or other like mechanism to accommodate theheads of the actuation screws 160 resulting in the heads being seatedbelow the outer end surface so to eliminate any possible surroundingtissue complications. Proximal plate 140 also includes a centralizedopening that is sized to permit the insertion of the locking insert 150that then transacts the thickness through the proximal plate 140 andextends the entire length of the device 100 before seating into theproximately positioned distal tip member 110. The outer aspect of thecentralized opening may include a counter bore or like configurationthat allows the head or end portion of the locking insert to seat belowthe outer end surface when it has been fully inserted and secured.

As seen in FIGS. 1, 2 and 3, the device 100 typically includes fourwings or fins 130 in its structure. The fins or wings 130 are movablerelative to the proximal plate 140, the middle plate 120 and the distaltip member 110. Generally, one pair of wings 130, which are in opposingpositions are secured between the proximal plate 140 and the middleplate 120. A second pair of similarly positioned wings 130 are securedbetween the middle plate 120 and the distal tip member 110. The wings130 are shown shaped in an arcuate/tear drop configuration to facilitateexpansion of the device in vivo. However, other shapes may be useddepending upon the given clinical circumstances. Further, the wings 130are shaped to maximize contact with the spinous processes withoutinterfering with the surrounding soft tissue. Disposed on the outer tipaspect of each wing are fixation means 180, which for example purposesare shown in FIG. 1 as sharpened protrusions. It would be understoodthat various other means for fixation 180 may be used including spikes,teeth, pins and other heightened surface iterations. Also seen in FIG. 1are holes 185. Holes 185 may be used to accommodate modular fixationmeans, including screws, pins and wires as well as being used tofacilitate insertion of the device 100. Holes 185 may be numerous foreach wing depending upon the given clinical situation. The range of thenumber of holes in each wing may be between 1-6, with a preferred rangeof between 1 and 4 holes. Wings 130 also include disposed on the curvedinner edge surface, a series of raised teeth or like locking mechanism.The teeth are positioned on the inner edge surface of the wing tomechanically interact with a corresponding tooth pattern that isdisposed on the top and bottom surface of the locking insert (see FIG.9). For example purposes, the top and bottom surfaces of the lockinginsert 150 each have a corresponding concave trough that runs the lengthof the insert. Running parallel to and within the trough are a series ofraised ribs which will interlock with the teeth of the wings 130. Thewings 130 may be rotated through the arc of curvature of the inner edgesurface and then secured when the appropriate orientation is achievedbetween the spinous processes. The range of rotation as measured from afully retracted position may be from 0 to 270 degrees, although otherdegrees of angulation are contemplated. As noted above, each of thewings 130 may also have a plurality of through holes 185 that are usedfor bone fixation, alignment purposes and securement within the deviceassembly.

FIG. 4 shows both the superior and inferior wings 130 locked at 210degrees from the fully retracted position. FIG. 5 shows the superior andinferior wings 130 locked at 150 degrees. Also shown in FIGS. 4 and 5 isthe locking mechanism for the wings 130 that includes the concave ribbedtrough of the locking insert 150 and the teethed portion of the inneredge surface of the wing. The superior and inferior wings are generallyindependent of each allowing the superior and inferior wings 130 to beangled to a different degree to address any anatomical issues orinsertion difficulties. Wings 130 are moved by a rotation mechanism,which for example purposes may be a press-fit connection betweenactuation screws 160 and holes 200 in wings 130. Other rotationmechanisms are contemplated, including a gear configuration, moveablespline, and camming arrangement.

FIGS. 10 and 11 show the device 100 following implantation between twospinous processes 300. FIG. 10 is a posterior view of the implanteddevice 100 with the superior spinous process captured between the twosuperior wings 130 and secured by the means of fixation which contactand grip the bone surface. With the inferior spinous processes, thisbone protuberance is also trapped between the two inferior paralleloriented wings 130. FIG. 11 is a lateral view showing the device 100 inplace following implantation within the spine. Wings 130 are in contactwith both lateral surfaces of the two adjacent spinous processes. Thedevice 100 is also seen to have an outer configuration such that theexternal profile of the device 100 does not extend beyond the apex ortip of either of the two processes. Because the device has a lowprofile, post operative soft tissue complications are decreased oreliminated.

FIG. 6 shows the locking insert 150 prior to insertion into thecentralized opening of the device 100. For example purposes, the lockinginsert 150 may be generally rectangular in shape with an overall lengththat mirrors the length of the device when assembled. It is contemplatedthat other cross-sectioned geometrics may also be used in theconstruction of locking insert 150. A central through hole extends theentire length and is sized to allow for the insertion of the innerlocking screw 170. The entry opening of the centralized hole may includea counter bore or like configuration to accommodate the head of theinner locking screw 170 and avoid potential soft tissue impingementissues. As discussed above, for example purposes, the top and bottomsurfaces of the locking insert 150 each have a concave trough that runsthe length of the insert. Running parallel to and within the trough area series of raised ribs or projections which will interlock withcorresponding teeth of the wings 130 to secure the wings position andform a locking mechanism. It is contemplated that other mechanicalconfigurations may be used to accomplish the locking of the wingsrelative to the locking insert, including possible frictional engagementbetween the wings 130, and plates 120, 140 and distal tip member 140.

FIG. 3 also shows inner locking screw 170 and superior and inferioractuation screws 160. The inner locking screw 170 is configured to passthrough the central portion of the locking insert 150 and then couple tothe distal tip member 110. The inner locking screw 170 functions to holdall of the components together when the assembly is constructed in askewer like fashion. It is contemplated that other mechanical fixationdevices may be used for this function, including locking pins or rods.For example, a compression o-ring may be used to lock the inner lockingscrew 170 to the device 100 to prevent backout. The superior andinferior actuation screws 160 are positioned above and below the lockinginsert 150 and may also apply a compressive load on the construct tolock the wings 130 in position. The actuation screws 160 extend throughall of the elements of the device, including the wings and couple to thedistal tip member 110 such that when tightened the actuation screws 160may apply a compressive load across the entire span of the device 100 tosecure all of the elements in position. It should be understood thatother alternative modes of fixation may be employed including, but notlimited to locking pins and rods.

As discussed above, the device operates in two states, expanded as shownin FIG. 1 and contracted as seen in FIG. 7. The surgeon utilizes thedevice in its contracted state when it is being implanted during a MISprocedure. The device 100 in its contracted position is fully assembledand includes the distal tip member 110, the middle plate 120, theproximal plate 140 with one pair of wings 130 sandwiched between thedistal tip member 110 and the middle plate 120 and the second pair ofwings 130 between the middle plate 120 and the proximal plate 140.Compressing the assembly is a temporary insertion insert 190 that has aconfigured end that is coupled to an insertion tool (not shown). In thecollapsed state, the device 100 has a uniform or cylindrical likeexterior profile that may be described as being bullet shaped. The wings130 have been internally rotated to the extent that the wings outeredges are fully within the outer boundaries/surfaces of the middle andproximal plates, hence producing a uniform outside profile to facilitateimplantation.

Once the device 100 is implanted between the superior and inferiorspinous processes the insertion insert 190 is removed, the wings 130 arerotated and expanded out and the locking insert is slid into the centralopening to secure the position of the wings 130. The inner locking screw160 is tightened to pressingly secure the assembly and the fix via thelocking mechanism (corresponding teeth/rib arrangement) the wings angledposition. In order to open the space for the wings 130 prior toinsertion of the device 100, a cutting tool 310 may be inserted into thesubcutaneous pathway to cut any soft tissue in the path of the wings130. As illustrated in FIGS. 12 and 13, the cutting tool 310 may have ahandle 312 and a blade 314.

The method of assembling the device 100 may include the steps ofchoosing a locking insert 150 sliding the proximal plate 140 over theinsert until it abuts the proximal end. A next step may be to insert thesuperior and inferior actuation screws 160 into the proximal plate 140.The method may then include the step of sliding a first wing 130 ontothe superior actuation screw 160 and a first wing 130 onto the inferioractuation screw 160 and sliding both wings 130 until they are adjacentto the proximal plate 140. The method may also include the step ofsliding the middle plate along the locking insert 150 and the twoactuation screws 160 until the middle plate 120 is adjacent to thepreviously positioned pair of wings 130. The method may also include thestep of sliding a second wing 130 onto the superior actuation screw 160and a second wing 130 onto the inferior actuation screw 160 and slidingboth wings 130 until they are adjacent to the middle plate 120. Themethod may include the step of selecting a certain sized distal tipmember 110 and sliding this onto the ends of the locking insert 150 andthe actuation screws 160. The actuation screws 160 may then be rotatedto adjust the angulation of the wings 130 and thereby thread into thedistal tip member 110. The method may also have the step of insertingthe inner locking screw 170 into the centralized hole of the lockinginsert 150 and then threading the end into corresponding threaded holedisposed within the distal tip member 110 to compress and secure theassembly into one construct.

Several biocompatible materials may be used to fabricate the elements,including a myriad of metals, polymers, ceramics and composites.Examples of these include PEEK, titanium and stainless steel.

The example minimally invasive surgical method for using the device 100includes the steps of inserting the device subcutaneously between thecephalad or top spinous process and the caudal or bottom spinous processwhile the device is in its collapsed state with the wings 130 retracted.This subcutaneous pathway may be created through an independentincision, or through the DLIF, TLIF, or unilateral decompression ofstenosis incision (1½ cm off midline). The method may also include thestep of positioning the device between the two spinous processes. Themethod may further include the step of deploying the wings 130 in boththe cephalad and caudal direction and on both sides of the spinousprocesses. The method may further include the step of compressing thedevice with the inner locking screw to pressingly engage from a lateralto medial direction the wings 130 with the two sides of the spinousprocesses. Sharp pins in the wings 130 hold the device in place. Oncethe device is secured, the tightening instrument is removed and theincision is closed.

More specifically, the surgical method for using the device 100 includesthe steps of creating an incision at the site where the implant will beinserted. Preparing the site for insertion of the device 100, by forexample, chiseling to cut or trim the spinous processes to accept thedevice 100. Then a series of a plurality of dilators of increasing sizemay be inserted to expand the space between the spinous processes. Forexample, a first circular dilator 240 could be inserted into an incisionin the patient. Then a second circular dilator 242 with a largerdiameter could be inserted over the first dilator 240 to increase thesize of the opening. It is also contemplated that only one circulardilator could be used. Alternatively, a plurality of circular dilatorscould be used. Next a third dilator 244 with a slightly oval shape couldthen be inserted over the second dilator 242 to increase the size of theopening. A fourth dilator 246 with a larger oval shape than the thirddilator 244 could then be inserted next over the third dilator 244,wherein the first, second, and third dilators 240, 242, 244,respectively, are in a center opening within the fourth dilator 244. Aplurality of additional dilators could then be inserted over the priordilator until a dilator having a size that matches the size of thedevice 100 has been used. As depicted the additional dilators mayinclude only one dilator, such as fifth dilator 248. Alternatively, theadditional dilators may include multiple additional dilators ofincreasing size. The circular dilators may have a diameter ranging fromapproximately 4 mm to 8 mm and a length ranging from approximately 20 mmto 50 mm. The oval dilators will have sizes ranging from a height ofapproximately 5 to 25 mm, with preferred sizes ranging from 7 to 22 mm,a width of approximately 4 to 16 mm, with a preferred width size of 5 to15 mm, and a length range of approximately 20 mm to 55 mm. An example ofa set of dilators is shown in FIG. 14.

Once the pathway has been enlarged to the size of the device 100, all ofthe dilators may be removed and trials of the device 100 may be insertedthrough the pathway to a space between the two spinous processes 300 todetermine the desired size of the device 100. The trials will haveexterior sizes that are equivalent to the sizes of the device 100 andmay contain a handle for ease of insertion and removal from the patient.For example, the trials may have a height of approximately 8 to 16 mm, awidth of approximately 4 to 8 mm, and a length of approximately 20 mm.When the surgeon determines which trial best fits between the twospinous processes 300, the surgeon will select the equivalent device 100and insert it into the patient. After the device 100 is inserted andpositioned between the two spinous processes 300, the plurality ofmovable wings 130 may be expanded to engage the spinous processes 300.After the plurality of movable wings 130 are expanded the device 100 maybe locked in the desired position and the patient may be closed up.

Although the example embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions and substitutions can be madewithout departing from its essence and therefore these are to beconsidered to be within the scope of the following claims.

What is claimed is:
 1. A surgical method for maintaining a space betweentwo spinous processes in a spine of a patient, comprising: obtaining amedical device comprising: a distal tip member, a middle plate, aproximal plate, an elongate member having a first end, a second end, anda longitudinal axis extending between the first end and the second end,and a plurality of movable wings, wherein the distal tip member isconnected to the first end of the elongate member and the proximal plateis connected to the second end of the elongate member with the middleplate and plurality of wings being positioned intermediate the distaltip member and the proximal plate along the longitudinal axis of theelongate member; inserting the medical device through an opening in theskin of the patient; positioning the medical device between a topspinous process and a bottom spinous process; moving the plurality ofwings to pressingly engage the top spinous process and the bottomspinous process to maintain the space therebetween; and inserting aninner locking screw into a hole in the elongate member to secure themedical device to the top spinous process and the bottom spinousprocess.
 2. The surgical method of claim 1, further comprising:inserting a first dilator through the opening in the skin of the patientprior to inserting the medical device, wherein the first dilator iscircular.
 3. The surgical method of claim 2, further comprising:inserting a second dilator through the opening in the skin of thepatient and over the first dilator prior to inserting the medicaldevice, wherein the second dilator is slightly oval.
 4. The surgicalmethod of claim 3, further comprising: inserting a third dilator throughthe opening in the skin of the patient and over the second dilator priorto inserting the medical device, wherein the third dilator is oval. 5.The surgical method of claim 4, further comprising: inserting aplurality of fourth dilators through the opening in the skin of thepatient and over at least one of the third dilator and the previousfourth dilator, wherein each fourth dilator of the plurality of fourthdilators is slightly larger than the previous fourth dilator, andwherein the plurality of fourth dilators are ovals of increasing size.6. The surgical method of claim 5, wherein the largest of the pluralityof dilators is sized to correspond with an exterior shape of the medicaldevice for insertion into the patient.
 7. The surgical method of claim5, wherein the plurality of dilators are sized to include a height ofapproximately 5 to 25 mm, with a preferred height ranging from 7 to 22mm, a width of approximately 4 to 16 mm, with a preferred width size of5 to 15 mm, and a length range of approximately 20 mm to 55 mm.
 8. Thesurgical method of claim 1, further comprising: closing the opening inthe skin of the patient.
 9. The surgical method of claim 1, wherein theplurality of movable wings comprises a first pair of movable wings and asecond pair of movable wings.
 10. The surgical method of claim 9,wherein the first pair of movable wings comprises a first fin and asecond fin and the second pair of movable wings comprises a third finand a fourth fin.
 11. The surgical method of claim 10, wherein each ofthe first fin, the second fin, the third fin and the fourth fin furthercomprise a lateral side and a medial side.
 12. The surgical method ofclaim 11, wherein the medial side is planar, and wherein the medial sideof the first fin and the third fin contact the top spinous process andthe medial side of the second fin and the fourth fin contact the bottomspinous process to maintain the space therebetween.
 13. The surgicalmethod of claim 12, wherein a fixation means extends from each of themedial sides of the first fin, the second fin, the third fin and thefourth fin to secure the medical device to at least one of the topspinous process and the bottom spinous process.
 14. The surgical methodof claim 13, wherein the fixation means comprises at least one ofspikes, teeth and pins, wherein the ends of the fixation means areconfigured to engage an outer bone surface of at least one of the topspinous process and the bottom spinous process.
 15. The surgical methodof claim 11, wherein each of the first fin, the second fin, the thirdfin and the fourth fin further comprise at least one opening, whereinthe at least one opening extends from the lateral side to the medialside of each of the fins.
 16. The surgical method of claim 15, whereinthe at least one opening is configured to accommodate at least one of ascrew, pin and wire to facilitate securement of the medical device to atleast one of the top spinous process and the bottom spinous process. 17.A surgical method for maintaining a space between two spinous processesin a spine of a patient, comprising: obtaining a medical devicecomprising: a distal tip member, a middle plate, a proximal plate, anelongate member having a first end, a second end, and a longitudinalaxis extending between the first end and the second end, and a pluralityof movable wings, wherein the distal tip member is connected to thefirst end of the elongate member and the proximal plate is connected tothe second end of the elongate member with the middle plate beingpositioned intermediate the distal tip member and the proximal platealong the longitudinal axis of the elongate member, wherein theplurality of movable wings are offset along the longitudinal axis,wherein the plurality of movable wings comprises at least a first pairof movable wings with a first wing and a second wing and a second pairof movable wings with a third wing and a fourth wing, and wherein in afirst position the first wing is positioned between the proximal plateand the second wing, the second wing is positioned between the firstwing and the middle plate, the third wing is positioned between themiddle plate and the fourth wing, and the fourth wing is positionedbetween the third wing and the distal tip member; inserting the medicaldevice through an opening in the skin of the patient; positioning themedical device between a top spinous process and a bottom spinousprocess; and rotating the plurality of wings to position the pluralityof wings to pressingly engage the top spinous process and the bottomspinous process to maintain the space therebetween.
 18. The surgicalmethod of claim 17, wherein rotating the plurality of wings comprisesdeploying each of the plurality of wings from the first position to asecond position, wherein a first set of the plurality of wings rotateseach wing of the first set from the first position where a first end issuperior to a central opening to the second position where the first endis inferior to the central opening, and wherein a second set of theplurality of wings rotates each wing of the second set from the firstposition where a first end is inferior to the central opening to thesecond position where the first end is superior to the central opening.19. The surgical method of claim 17, wherein the medical device furthercomprises: a temporary insert positioned within a central opening of atleast the proximal plate; and wherein the method further comprises:removing the temporary insert from the medical device before rotatingthe plurality of wings.